Scientific controversy has arisen over whether subtle changes in social behavior accompany marijuana smoking and whether changes in behavior or performance persist into the post-intoxication period. Such questions can only be addressed by dose-response studies of marijuana effects on behavior under controlled laboratory conditions. This project will determine the effects of acute marijuana smoking in human social behavior and performance in a controlled laboratory setting. The time-course effects of marijuana will be monitored during acute intoxication and during the immediate post- intoxication period. Initial studies will compare an automated spirometry inhalation method marijuana administration. Several functional standard paced puffing procedure for marijuana administration. Several functional classes of human social behavior will be studied: (1) aggressive responding occasioned by provocation, (2) competitive behavior, (3) cooperative behavior and (4) work related behavior. These experiments will determine the acute effects of marijuana and possible residual effects which may alter probabilities that subjects will aggress following provocation, engage in competition when non-competitive response alternatives are available, choose to cooperate with other subjects, and choose to work to earn money. Such data will provide information regarding marijuana effects on different basic classes of human social behavior. In addition, the acute effects on different basic classes of human social behavior. In addition, the acute effects of marijuana on memory and performance will be assessed by studying the effects of marijuana on a delayed matching-to-sample and a number recall task. These studies will also employ traditional rating scales to help quantify the dose relationship of marijuana intoxication and how these subjective effects may relate to performance impairment. Collectively, the project will assess acute dose effects of marijuana on human social "interaction", subject ratings and performance under controlled laboratory conditions, allowing the detection of changes in behavior and performance during acute intoxication and possible residual effects during post-intoxication interval.